1. Cycling maintains homeostasis (balance) in the environment.
Nutrient Cycles
Cycling maintains homeostasis (balance) in the environment.
3 cycles to investigate:
1. Water cycle
2. Carbon cycle
3. Nitrogen cycle

2. Water cycle-
Evaporation- is a type of vaporization of a liquid to gas phase from the surface of a liquid.
Transpiration- evaporation of water from plant leaves.
(diagram on next page)
Condensation- change of the physical state of matter from gas phase into liquid phase, and is the reverse of evaporation.
Precipitation- any product of the condensation of atmospheric water vapor that falls under gravity.

4. Water cycle-

5. Carbon cycle-
Photosynthesis and respiration cycle
carbon and oxygen
through the environment.

6. The chemical equation for photosynthesis is:
6CO2 + 6H2O > C6H12O6 + 6O2 Sunlight energy
CO2 = carbon dioxide H2O = water Light energy is required C6H12O6 = glucose O2 = oxygen
The chemical equation for respiration is:
C6H12O6 + 6O CO2 + 6H2O
Glucose + Oxygen Carbon Dioxide + Water

7. Carbon cycle-

8. Nitrogen cycle-
Atmospheric nitrogen (N2) makes up nearly 78%-80% of air.
Organisms can not use it in that form.
Lightning and bacteria convert nitrogen into usable forms.

9. Nitrogen-fixing bacteria: rhizobacteria
Nitrogen cycle-
Nitrogen-fixing bacteria: rhizobacteria
Some live in a symbiotic relationship with plants of the legume family (e.g.,alfalfa soybeans, clover, peas, peanuts).

10. Nitrogen cycle-
Some nitrogen-fixing bacteria live free in the soil.
Nitrogen-fixing bacteria:
cyanobacteria are essential to maintaining the fertility of semi-aquatic environments like rice paddies.

11. Nitrogen cycle-
Only in certain bacteria and industrial technologies can fix nitrogen.
Nitrogen fixation-convert atmospheric nitrogen (N2) into ammonium (NH4+) which can be used to make organic compounds like amino acids.
N2 NH4+

13. Nitrogen Cycle Atmospheric nitrogen Lightning
Denitrification by bacteria
Animals
Nitrogen fixing bacteria
Plants
Decomposers
Nitrification by bacteria
Nitrites
Nitrates
Ammonium

14. This is called biological magnification
Toxins in food chains-
While energy decreases as it moves up the food chain, toxins increase in potency.
This is called biological magnification
Ex: DDT & Bald Eagles